Applies to:

Oracle Net Services - Version 9.2.0.4.0 to 12.1.0.2 [Release 9.2 to 12.1]Information in this document applies to any platform.
This problem can occur on any platform.
This issue can occur in 9.2.0.x with Security patch #68 applied, or any later version of Oracle.

Symptoms

You have TCP.VALIDNODE_CHECKING enabled in the sqlnet.ora file and the listener is failing to start with one of these error stacks: